|Title of Invention||
REACTOR FOR A CATALYTIC CONVERSION REACTION
|Abstract||Reactor for a catalytic conversion reaction comprising within a catalyst housing a perforated catalyst support plate supporting a catalyst bed, the perforated catalyst support plate being supported by a plurality of elongated support elements, and catalyst particles in the catalyst bed being placed outside the elongated supported elements, the perforated catalyst support plate being attached to the lower ends of the elongated support elements, the perforated catalyst support plate being divided into a plurality of perforated catalyst support plate segments, at least one perforated catalyst support plate segment being supported by an elongated support element.|
REACTOR FOR A CATALYTIC CONVERSION REACTION
The invention relates to a catalytic reactor that is constructed to reduce deformation and rupture of the reactor internals. In particular it relates to a catalytic reactor with an improved catalyst housing.
BACKGROUND OF THE INVENTION
In heterogeneous chemical reactions the chemical reaction is often catalysed by solid catalyst particles. These catalyst particles are typically located in catalyst beds, and during passage of a reactive fluid through the catalyst bed, a chemical reaction takes place, thereby converting the reactive fluid into the desired product or mixture of products having a chemical composition different from that of the reactive fluid.
The inner contents of a reactor are known as reactor internals. The catalyst bed is kept in position in the reactor by reactor internals which allow fluid passage to and from the catalyst particles. This is commonly done by perforating the reactor internals in contact with the catalyst particles. The nature of the perforation determines the fluid flow pattern inside the catalyst bed.
The reactor internals for keeping the catalyst bed in position are typically a catalyst support plate supported along its edges and/or on the free side opposite the catalyst side. In some cases it is not feasible to support the catalyst support plate on this free side, as for example is the case when the catalyst particles and the catalyst
An alternative method of supporting the catalyst support plate is by using various supporting structures placed in the catalyst bed and fixed on the catalyst support plate. This allows the use of larger catalyst support plates in comparison to fixing the support plate to the catalyst housing walls. Supporting structures such as stays fixed on the catalyst support plate can be used. Stays are supportive elements fixed at one end to a first structure and at its other end to a second structure, providing support to one or both of the structures.
However, stays and such similar supporting structures can have differences in thermal expansion due to unequal temperature distribution in the reactor. This causes high stress effects within the catalyst support plate and in the stays in the axial direction, and this can lead to their deformation or rupture. The forces experienced by these particular reactor internals in the radial direction are negligible compared to.the forces in the axial direction .
The English abstract of JP patent application No. 49010172 discloses a catalytic reaction apparatus useful in high temperature catalytic reactions for avoiding rupture of the catalyst supporting plate. The catalyst supporting plate has holes and is partitioned into one or more regions and a supporter for the catalyst-supporting plate. Both are fastened with vertical bolts. The thermal expansion of the catalyst supporting plate can be absorbed by loosening the bolts between the plate and its supporter so that they can slide relative to each other.
Fig. 5 is a schematic diagram showing a longitudinal section through the catalyst housing with tubes fixed at their lower ends to the segmented catalyst support plate. Fig. 6 is a schematic diagram showing a longitudinal section through the catalyst housing with double tubes fixed at their lower ends to the segmented catalyst support plate.
Fig. 7 is a schematic diagram showing a transverse section of the segmented catalyst support plate with segments attached either to the catalyst housing wall or to the elongated support elements.
DETAILED DESCRIPTION OF THE INVENTION
The catalytic reactor of the invention includes a catalyst housing comprising a plurality of elongated support elements. Within the catalyst housing is a perforated catalyst support plate for supporting a bed of catalyst particles. The elongated support elements are, at their lower ends, fixed to the perforated catalyst support plate, for instance by means of welding. The perforated catalyst support plate is segmented and each catalyst support plate segment is supported by an elongated support element. The assembly consisting of segmented catalyst support plate and elongated support elements fixed on these catalyst support plate segments are supported by a tube sheet or plate onto which the upper ends of the elongated support elements are fixed.
through the aperture into the volume below the catalyst support plate.
In order to avoid this situation, the minimum thickness of each catalyst support plate segment should be, under all process, start-up and shut-down conditions, at least equal to the largest possible difference in extension between two neighbouring elongated support elements.
The segmented catalyst support plate can be made of any suitable material. Examples are nickel alloys and stainless steel.
The elongated support elements can have a transverse cross-section that is cylindrical. Other cross-sectional shapes are also possible, e.g. a hexagonal or square cross-section. In other words, the transverse cross-section can be polygonal in shape.
The catalytic reactor of the invention is suitable for use at a wide range of temperatures. It is particularly suitable for use at temperatures above 700°C in reactors, where the stays can experience a large variation in temperatures leading to significant variations in thermal expansion .
Each catalyst support plate segment is attached to at least one elongated support element. However, catalyst support plate segments bordering the wall of the catalyst housing can optionally be fixed to this wall while the remaining catalyst support plate segments are attached to the lower ends of the elongated support elements.
this embodiment the catalyst support plate segments 2 and 3 are respectively four and six sided.
However, each catalytic support plate segment can be cut in different shapes as illustrated in Fig. 2. Fig. 2 shows a transverse section through a catalyst housing in a catalytic reactor of the invention comprising a plurality of elongated support elements 4 fixed to a plurality of catalyst support plate segments 2 and 3 with perforations S. This embodiment shows catalyst support plate segments 2 and 3 that are respectively hexagonal and pentagonal in shape, and the length of the sides of the catalyst support ..plate segments can vary i.e. they are not identical in length, as shown in catalyst support plate segment 2. Catalyst support plate segments that are triangular or square in shape are also useful in the catalytic reactor of the invention. The catalyst support plate segments 2 can therefore be polygonal in shape. In this embodiment the elongated support elements are cylindrical and consist of concentric double tubes.
Fig. 3 shows a variation of the embodiment shown in Fig. 1. In this embodiment, the central catalyst support plate segment is eliminated and the peripheral catalyst support plate segments 3 are cut such that they border the central elongated element placed in hole 4. In this case, the central elongated element in hole 4 does not support any of the catalyst support plate segments 3.
All the catalyst support plate segments are supported. However not all the elongated elements in the catalyst bed provide support to a catalyst support plate segment. The
tions 5 and the gaps 6, if present, to enter the volume 9 downstream the catalyst bed 7 .
Another embodiment of the invention is shown in Fig. 5. In this embodiment the catalytic reactor of the invention is similar to that described in Fig. 4 with the exception that the elongated support elements are tubes 3 through which a process fluid can flow with the lower ends of the tubes being fixed to the catalyst support plate segments 4 . Only the catalyst housing and its contents are shown in this figure. A process fluid enters the catalyst housing 2 through the inlet 8 and is converted during passage... through the catalyst bed 7. After passage through plate segments 4 the reacted process gas enters the volume 9 and thereafter the tubes 3 through their lower ends. During passage through the tubes 3 the reacted process gas can be in indirect heat exchange with the reacting process gas in the catalyst bed 7.
This embodiment is suitable for use in a steam reforming reaction in which methane is reacted with steam to produce carbon monoxide and hydrogen. The endothermic steam reforming reaction takes place in the catalyst bed 7, and the product gas enters volume 9 and is mixed with hot gas entering from inlet 10. The mixture is thereafter, during transfer through the tubes 3, cooled by heat exchange with the reaction occurring in catalyst bed 7. The reacted gas leaves the catalyst housing 2 through the outlet 12.
The embodiment shown in Fig. 5 is particularly useful in steam reforming reactions where temperatures as high as 1000°C are experienced. In such reactors a reactor tube,
the volume 13 of the inner tube 6 of the concentric double tube 3. The process gas is simultaneously converted during passage through catalyst bed 7 located outside the concentric double tubes 3. The converted process gas leaves the volume 13 of the inner tube 6 of the concentric double tube 3 and enters the volume 9. The converted process gas also leaves the catalyst bed 7 through the perforated segmented catalyst support plate 4 and enters the volume 9. The converted process gas in volume 9 can then be mixed with another gas entering catalyst housing 2 through inlet 10. The process gas mixture is thereafter transferred through the annulus 5 of the concentric double tubes 3 to the outlet 12.
Another preferable embodiment of the invention is the catalytic reactor in which the catalyst support plate segments are fixed to either an elongated support element or to the vertical wall of the catalyst housing as shown in Fig. 7. In this embodiment some of the catalyst support plate segments 1 bordering the vertical wall of the catalyst housing are fixed to and supported by the vertical wall. The remaining catalyst support plate segments 2 are fixed to and supported by elongated support elements placed in the hole 3.
7 . Reactor according to claim 5, wherein the concentric double tubes contain catalyst inside the inner tube and process gas in the annulus.
8. Reactor according to claims 1-3, wherein the catalyst support plate segments are polygonal in shape.
9. Use of the reactor according to anyone of claims 1
to 9 in a steam reforming reaction.
|Indian Patent Application Number||2623/CHENP/2007|
|PG Journal Number||09/2013|
|Date of Filing||18-Jun-2007|
|Name of Patentee||HALDOR TOPSOE A/S|
|Applicant Address||Nymøllevej 55, DK-2800 Kgs. Lyngby (DK)|
|PCT International Classification Number||B01J 8/02|
|PCT International Application Number||PCT/EP05/13284|
|PCT International Filing date||2005-12-12|